A known motor is illustrated in FIG. 5, with an end cap removed to show a cover 106 and a circuit board 102 of an end cap assembly. The circuit board 102 is disposed inside the cover of the end cover assembly, and electronic elements 104 such as Hall sensors are electrically mounted on the circuit board. To save cost, the cover is usually made of a plastic material. When subjected to high-voltage static electricity, the plastic cover cannot dissipate the static electricity. The static electricity passes through the plastic cover to the circuit board where usually the static electricity is strong enough to damage the electronic elements mounted on the circuit board, including any Hall sensors.